Objectives: 1. Isolation and characterization of components involved inthe mitochondrial electron transport-oxidative phosphorylation system. 2. Study of the enzymatic properties of these components in isolated form and reconstituted systems. 3. Study of the mechanistic details of energy coupling by resolution-reconstitution studies, and by photoaffinity labelling of the mitochondrial coupling sites. 4. Study of struAture-function relationships and control mechanisms in mitochondria, sub-mitochondrial particles, electron transfer complexes, and in individual enzyme components of the mitochondrial energy generation-conservation system. Recent, unpublished studies have included: a. Demonstration by epr that the site of TPNH interaction with the electron transport system is at the level of iron-sulfur centers 2 and 3 of complex I. b. Kinetics and controls of cytochrome b reduction in submitochondrial particles. c. Details of the TPNH-cytochrome c reductase properties of the complex I-III. d. Characterization of the uncoupler-binding proteins of mitochondria. e. Determination of the amino acid composition of the iron-sulfur flavoprotein and iron-sulfur protein subunits of succinate dehydrogenases purified from bovine heart mitochondria and Rhodospirillum rubrum.